Method and apparatus for forming and hermetically sealing slices of food items

ABSTRACT

An apparatus and method for continuously forming hermetically sealed packages of a food item. A continuous web of thermoplastic material is folded and continuously formed with a hermetic longitudinal seal. The food item is inserted between inner surfaces of the tubular web member, which is then flattened to form a thin slice. A hermetic cross-seal is continuously formed transverse to the longitudinal seal. The web can be cooled before the cross-seals are formed.

This application is a continuation of U.S. Ser. No. 08/098,752, filed onJul. 28, 1993, now U.S. Pat. No. 5,440,860, which is a continuation ofU.S. Ser. No. 07/791,490, filed Nov. 12, 1991, now abandoned, which is acontinuation-in-part of U.S. Ser. No. 07/644,481, filed Jan. 18, 1991,now U.S. Pat. No. 5,114,307, which is a continuation of U.S. Ser. No.07/361,405, filed Jun. 5, 1989, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates generally to an apparatus and method forpackaging food items and more particularly to an apparatus and processfor packaging and stacking food items in hermetically sealed individualslices.

Various methods and apparatus have been proposed and utilized for themanufacture and packaging of individual slices of food items such ascheese. Although the available apparatus and methods are suitable forthe packaging of individual slices, they are not without disadvantages.

Typically, the package for the individual slices is formed from acontinuous film or web of a thermoplastic material. The web is firstfolded in V-folded condition. As used herein, the term V-foldedcondition refers to a length of material which has been folded over ontoitself so as to form what may subsequently be identified as a frontsheet and a rear sheet which are joined by the fold at the bottom, so asto approximate the letter "V" in cross section. The web is typicallyfolded such that the rear sheet is longer than the front sheet to definea flap section in the rear sheet, which extends beyond the top edge ofthe front sheet. The flap section is typically folded over onto thefront sheet to form a tubular web.

After the flap is folded over on the front sheet, a tubular web isdefined. The processed cheese is then inserted into the tube and the weband cheese are flattened. Subsequently cross-seals are formed along thelongitudinal length of the tubular web at predetermined intervals. Afterthe tube is cross-sealed it is severed along the cross-seals in order toproduce the individually wrapped slices of cheese. Several processespresently exist for providing the transverse or cross seal.

In one commonly used method, the cross-seals are formed by subjectingthe flattened web (with the inserted cheese) to pressure, at the desiredlocation, to form the transverse cross seal. The pressure is appliedsuch that an ultra thin layer or film of cheese is left in thetransverse sealing section. The ultra thin layer or film of cheese actsas an adhesive to seal the two layers of the plastic web together. Afterthis "cheese" seal has been formed, the web is severed at the sealedsections to define individual slices of cheese.

Although the "cheese" seal provides an adequate seal for the individualslices of cheese, the shelf life of the cheese product after it ispackaged is not as long as would be desirable. This is due to the factthat the cheese seal is a relatively weak seal which will eventuallydeteriorate and which allows air to enter into the slices under ordinaryatmospheric conditions. The slices will soon dry out or spoil.

Other methods of providing a transverse cross-seal have also beendisclosed. For example, U.S. Pat. No. 4,586,317 (Bussell) discloses anarrangement for forming a seal in packaging material (such as processedcheese) which utilizes a sealing element having a finite number of smallchannels in the surface. The packaging film is co-extruded or laminatedto include an inner sealing layer of relatively low thermal plastic melttemperature and an outer layer which does not melt under sealingconditions. The tube is heated and compressed transversely by thesealing elements thereby sealing the internal layers of the packagingfilm together. Although the apparatus and method disclosed in thispatent provide a suitable cross-seal, the finished product suffers fromthe same disadvantages that are described above. Since the longitudinalseal is formed by providing a flap in the V-folded condition web andsimply overlapping the flap with the upper surface of the front sheet ofthe web, a poor seal is formed. Thus, air and other atmospheric productswill enter into the wrapped slices of cheese, reducing the shelf life ofthe product.

Therefore it would be desirable to provide an individual slice of cheesewhich is wrapped in a package which is hermetically sealed on all sides.To accomplish this, a hermetic seal must be formed along thelongitudinal edge of the web as well as along the transverse orcross-seals. A hermetically sealed package would have severaladvantages. For example, a hermetically sealed slice would permitimmersion for cooling and sanitizing. Further, a hermetically sealedslice is essential to aseptic packaging.

For purposes of manufacturing economy, it would be desirable to providethe longitudinal seal and cross-seals in a continuous process. Somepresently available methods, however, form seals in an intermittentfashion. Typically, in these presently available methods, a seal isformed by heated jaws which reciprocate between an open and a closedposition. When the jaws close, they seal the desired section of the web.After the section has been sealed, the jaws retract and the web is movedfor the next section which is to be sealed. This process, however, hasobvious disadvantages. The web must be continuously stopped and startedin accordance with the reciprocating movement of the jaws. Such a deviceis disclosed for example in U.S. Pat. No. 2,460,460 (Langer).

Another problem which is encountered in the processing and packaging ofcheese slices (as well as in the packaging of other products which arepackaged in slices) is the lack of an available simple and efficientstacking process. Typically the stacking of slices into packagescontaining a plurality of slices is performed by an operator or astacking machine. The available stacking machines, however, do notprovide the required degree of efficiency and precision in the packagingof different stacks of cheese. It would be desirable to provide astacking arrangement or process which would permit slices from a singlewrapping machine to be stacked in a plurality of different stacks. Itwould be even more desirable to provide an arrangement which would allowthe operator to selectively vary the number of slices in the stacks fromone stacking job to the next. Preferably the stacking arrangement willalso accurately stack slices of cheese from a relatively fast productionline in a plurality of different stacks.

Therefore, in view of the above, it is an object of the presentinvention to provide an apparatus and a method for producing individualslices of food items, such as processed cheese, which are hermeticallypackaged.

It is a further object of the present invention to provide an apparatusand method for providing a continuous and efficient arrangement forforming hermetic seals along all of the edges of the packaging web.

It is still a further object of the present invention to provide anapparatus and method for stacking the desired number of the slices offood items, such as cheese, in the stacking locations from a rapidpackaging system.

SUMMARY OF THE INVENTION

To achieve the foregoing and other objects and in accordance with thepurposes of the present invention, an apparatus and method are providedfor forming a hermetically sealed package for a slice of a food item. Aweb of thermoplastic material is first formed into a tubular arrangementwith a hermetic longitudinal seal. To form the tubular arrangement,means are provided for folding a continuous web of thermoplasticmaterial into V-folded condition and for continuously forming a hermeticseal along the open longitudinal edge of the V-folded web. The hermeticseal is formed between the inner surfaces of the front and rear faces ofthe web to define a tubular web member. The cheese which has been formedinto a soft mass, is then inserted into the tubular member and thetubular member is flattened to form a continuous web. Means are providedfor forming hermetically sealed cross-seals which are disposedsubstantially transverse to the longitudinal forward moving direction ofthe web.

In a preferred embodiment of the invention the means for forming thelongitudinal seal include a pair of stationary plates with opposedundulating surfaces. The plates are arranged such that a fixedpredetermined distance is defined between the undulating surfaces of theplates. The plates are heated and the web is passed through the spacebetween the two plates. As the web moves through the plates, theundulating surfaces alternatively force the front and rear faces of theweb into intimate contact with each other to thereby form a hermeticlongitudinal seal without clamping the film between the surfaces.

In another aspect of the invention, a stacker is provided for stackingthe slices from the wrapping and cutting machines into a plurality ofstacks. The stacker includes a conveyor belt, which includes a pluralityof apertures, onto which the slices of cheese are disposed. A vacuumsystem provides vacuum through the apertures to hold the slices ofcheese on the belt. Means are provided for moving the belt in order toadvance the slices of cheese to the stacking locations. The vacuum issufficient to hold the slices of cheese on the belt even when the slicesare disposed on the bottom of the belt. A plurality of stackinglocations are sequentially provided. Each of the stacking locationsincludes means for providing positive air pressure at the leading edgeof the cheese slice as it approaches each stacking location while it isbeing moved on the belt. As the cheese travels on the belt, the positiveair pressure overrides the vacuum forces holding the slice on the beltthereby "peeling" the cheese slice off of the belt and the force ofgravity causes the slice of cheese to fall into the predeterminedstacking location. In a preferred embodiment, means are provided forselectively engaging or disengaging the positive air pressure at theleading edge of each stacking location. This stacking arrangement thusprovides an apparatus for stacking a predetermined number of wrappedcheese slices being produced at a relatively rapid production rate intoa plurality of stacks.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing or may be learned by practice of the invention. The objectsand advantages of the invention may be obtained by means of thecombinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a preferred embodiment of theapparatus and method of the present invention including the longitudinalsealer, the cross sealer, and the stacker.

FIG. 2 illustrates a preferred embodiment of a slice of cheese which hasbeen sealed with the process and apparatus of the present invention(with the flap folded over).

FIG. 3 illustrates the slice of cheese illustrated in FIG. 2 with theflap unfolded.

FIG. 4 is an illustration of a preferred embodiment the longitudinalsealer and flattening means of the present invention.

FIG. 5 is a schematic representation of the cross sealer and stackerillustrated in FIG. 1.

FIG. 6 is a top view of a preferred embodiment of the stackerillustrated in FIG. 1.

FIG. 7 illustrates a side view of the preferred embodiment of thestacking arrangement illustrated in FIGS. 1 and 6.

FIG. 8 is an illustration of a preferred embodiment of the longitudinalsealer of the present invention.

FIG. 9 illustrates an enlarged side view of a section of the crosssealing arrangement illustrated in FIG. 1.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like elements arereferred to with like reference numerals throughout the variousdrawings. Referring specifically to FIG. 1, a preferred embodiment ofthe arrangement and process of the present invention including thelongitudinal sealer, cross sealer, and the stacker is illustrated.

Cheese is first processed, in a manner known in the art, by cheeseprocessing means 10. The processed cheese is then transferred, in aknown manner, from the cheese processing means 10 into a fill tubearrangement 12 which is used to insert the processed cheese into atubular web made of thermoplastic material.

In more detail, the tubular web of thermoplastic material is formed byproviding a continuous film or web of thermoplastic material and foldingthe web into V-folded condition, in a manner known in the art. After theweb of thermoplastic material has been folded, a longitudinal seal isformed at a sealing station 20 (in a manner described in more detailbelow). Nip rollers 16 are provided to secure the seal and continuouslypull the Web of thermoplastic material. After the longitudinal seal isformed at the sealing station 20 and leaves the nip rolls 16, the cheeseis inserted by means of the fill tube 12 into the tubular web. The weband cheese are then passed to a flattening station 22 (also described inmore detail below). At the flattening station 22, the tubular web withthe cheese is flattened to form a continuous web or slice of cheese.

After the web has been flattened and formed into the film, the web isthen passed through a cooling station 14. In one preferred embodiment,the cooling station 14 comprises a tank or container for holding acooling liquid, such as water. In this embodiment, the cooling station14 may include a plurality of rollers such that the web and cheese arepassed through the tank in a winding fashion. Preferably the coolingstation 14 is configured such that the web with the cheese passesthrough the cooling water for approximately 20 seconds with the waterbeing at between 32° F. and 50° F. This will take the cheese whichusually starts off at a temperature of between 170° F. and 180° F. andcool the cheese down to approximately 50° F. at the exiting end of thecooling station 14. Preferably, the cooling station includes a rollerwhich is over driven to provide means for keeping the web taut. Thecooling station may also include scrapers and/or air-blowers (not shown)to dry the web as it exits from the cooling station 14. It will berecognized by those skilled in the art that other suitable cooling meansmay also be used.

After leaving the cooling station 14, the web is conveyed, preferably bya pair of driven feed belts 39, to the station which forms the crossseals. A loop control means and tensioning means 41 may be provided. Thetransverse or cross sealing station 40 includes a first member 42 with aplurality of heated jaws 46 and an opposed bottom member 44 with jaws 50with opposed engaging surfaces. The cross sealing station 40 provides ahermetic seal 102 transverse to the longitudinal or forward movingdirection of the web. The web now includes a plurality of slices ofcheese 100 which are hermetically sealed. The cross sealing station 40is described in more detail below.

After the transverse or cross seals have been formed, the web is thenconveyed to a cutting station 60 to separate the individual slices ofcheese 100. The station 60 includes means for cutting the web along thecross-seal to define the individual slices. The station 60 alsopreferably includes a stacking arrangement 70 which stacks the slices100 being conveyed from the cross sealing station 40 into a plurality ofstacks. The stacking arrangement is described in more detail below.

THE LONG SEALER

Referring now specifically to FIGS. 4 and 8, a preferred embodiment ofthe longitudinal sealing arrangement 20 and the flattening arrangement22 are illustrated.

The preferred embodiment of the longitudinal or long sealing arrangement20 provides a novel and advantageous apparatus and process for formingthe longitudinal seal in the web without stopping the web in anintermittent fashion. The sealing station 20 includes a pair ofstationary heated plates 24, 25. Each plate includes an undulatingsurface which forms an important part of the longitudinal sealer 20. Theundulating surfaces of the plates 24, 25 are opposed and the plates 24,25 are disposed such that a fixed gap or distance exists between theopposed undulating surfaces. The gap between the undulating surfaces ofthe plates 24, 25 is fixed such that as the front and rear sheets of theopen longitudinal edge of the web are conveyed between the undulatingsurfaces, the front and rear sheets of the web are forced into intimatecontact with each other.

In a preferred embodiment the gap between the undulating surfaces istapered having a wider gap at the top than the bottom with an averagegap distance of approximately 1/32 of an inch when high densitypolyethylene is used for the web material. An average gap distance ofapproximately 1/16 of an inch is desired when polypropylene is used forthe web material. The gap distance is dependent on such factors as thethickness of the slice, the machine speed, and the type of film used towrap the slice. Means are provided for heating the two plates to atemperature sufficient to form a longitudinal hermetic seal as the webis conveyed between the two plates 24 and 25 without physically clampingthe two surfaces together. The heating may be provided by any suitableheating means, for example, an electric heater 26 which is insertedlongitudinally through an aperture 23 in each plate 24, 25. The platesare heated to a temperature sufficient to form a hermetic seal betweenthe two sheets of the web, for example, the plates may be heated to atemperature of approximately 230°-240° F. when high density polyethyleneis used for the web material. The plates may be heated to approximately260° F. when polypropylene is used for the web material. Nip rollers 16are provided after the sealing plates station 20 to secure the seal andpull the web through the longitudinal sealer.

In a preferred embodiment, the fill tube 12 extends down into the websuch that the exiting edge of the fill tube 12 is disposed after the niprollers 16. In this manner, the cheese is inserted into the web afterthe longitudinal seal has been formed and a tube has been defined.

In a preferred embodiment, a bubble control element 28 is disposedbefore the flattening station 22. The bubble control unit 28 functionsto determine the amount of cheese which is being inserted into the web.In this manner, the flow of cheese may be controlled as appropriate forthe speed of the web and the desired thickness and weight of the slice.After the cheese is inserted into the tubular web, the tubular web isconveyed to a flattening station 22. The flattening station 22 includesa first or upper set of juxtaposed rollers 32, a lower set of juxtaposedrollers 34, and a pair of opposed belts 30. Each belt 30 is disposedaround one set of rollers 32, 34. As the web with the cheese insertedtherein passes between the two belts, the cheese is flattened to form aweb comprising the tubular thermoplastic film and a continuous slice ofcheese. Means 36 are provided in the flattening station 22 for adjustingthe distance between the belts 30 to control the thickness of the web oftubular thermoplastic material and cheese.

As illustrated in FIG. 3, the web is formed into a tubular section witha hermetically sealed longitudinal seal 106 (the longitudinal seal isrepresented in FIG. 3 by the section illustrated between the arrows).Preferably, the web is sealed along the top longitudinal edge of thefront face of the web such that a flap portion 104 is defined asillustrated in FIG. 3.

After the longitudinal seal 106 is formed, the web is conveyed throughthe cooling station 14, as described above, and then the flap 104 isfolded over onto the front face of the web as illustrated in FIG. 2. Theflap may be folded over in a manner known in the art before the webreaches the cross-sealing station 40. Preferably, the flap 104 ispartially sealed at the cross seal sections to the front face of the webat the cross sealing station 40.

THE CROSS SEALING STATION

Referring now specifically to FIGS. 5 and 9, a preferred embodiment ofthe cross-sealing arrangement is disclosed. The cross-sealingarrangement includes an upper sealing member 42 and a lower sealingmember 44, with each of the sealing members including a plurality ofopposed jaws or cleats 46 and 50 respectively. As best illustrated inFIG. 9, the sealing members 42 and 44 are arranged such that as the webis conveyed through the sealing station 40 between the upper cleat 46and the engaging lower cleat 50 the top and bottom layers of the filmweb are urged into intimate contact with each other at a plurality ofcross-sealing zones while the web is continuously moved forward in thedesired cross sealing section. The cleats 46 of the upper member 42 areheated to the sealing temperature, in a manner known in the art. Forexample, the top cleat 46 may be heated by an electrical heater andbrush arrangement. The cleats 46 and 50 may be made of any suitablematerial such as aluminum. The top cleat 46 preferably includes aremovable section 48. The engaging bottom cleat 50 also preferablyincludes a removable section 45, which is made of a softer material thanthe top mating section 48 of the cleat 46. For example, the removablesection 48 of the top cleat 46 may be made of a metallic material suchas aluminum and the removable section 45 of the lower cleat 50 may bemade of a resilient material such as silicone or polyurethane. Siliconeis preferably used when high density polyethylene is the web materialand polyurethane is the preferred material when polypropylene is the webmaterial.

For purposes of quality control and to achieve uniformity in the crossseals, each of the heated cleats 46 includes a central temperaturecontrol having a microprocessor to control the current a power modulesupplies to each individual cleat. In another embodiment, individualthermostats 54 may be used to control the temperature of each individualcleat. Therefore the temperature of each cleat can be adjustedseparately.

Means are provided for urging the two opposed cleats to engage the webof cheese as it is conveyed through the sealing station 40. Asillustrated in the figures, in the preferred embodiment, the means forurging the cleat together comprises a track and chain arrangement. Eachof the cleats is attached to a chain arrangement which rides on a track56, 58. The chain arrangement, illustrated best in FIG. 9, includessections of chain including rollers 52 and 53 which are attached atspaced intervals to the links of the respective chain. The rollers 52,53 ride on elongated circular tracks 56, 58, respectively. The elongatedcircular tracks 56, 58 are disposed such that the cleats 46 and 50 ridein engaging relationship for a predetermined interval such that Whencleats 46 and 50 are in an engaging relationship heat is applied to theplurality of cross-sealing zones (discussed in more detail below).

Preferably the web of cheese in the tubular film is conveyed through theopposed jaws 46, 50 of the sealing members 42, 44 such that a hermeticseal is formed between the two inner layers of the web material. Morepreferably, the seal is formed such that when after the seal has beenmade and the package is pulled apart at the seal, the seal will break.This is opposed to the seals which are presently made wherein after theseal has been formed and the package is pulled apart, the seal is brokenby delamination, that is, by breaking the bond between the topnon-sealing layer of and the inner or sealing layer of the sheet of theweb. This preferred packaging arrangement is achieved by properselection of the thermoplastic material. For example, one preferredmaterial to be used for processed cheese with or without preservativescomprises a high density polyethylene (HDPE) layer coextruded with apolyethylene sealant layer with an intermediate adhesive layer.

While a high density polyethylene layer coextruded with a polyethylenesealant layer with an intermediate adhesive layer is the preferredpackaging material for cheese, other materials can be used for packagingcheese with the present invention. One group of materials aremanufactured by coextruding multiple layers as described previously. Thematerials can comprise 1) a polypropylene layer coextruded with apolyethylene sealant layer with an intermediate heat activated adhesivelayer; 2) a high density polyethylene layer coextruded with an oxygenbarrier layer with an intermediate heat activated adhesive layer; or 3)a polypropylene layer coextruded with an oxygen barrier layer with anIntermediate heat activated adhesive layer. An oxygen barrier layer suchas EVOH, Saran, etc. may be employed with meats and food products thatdo not contain food preservatives.

Another group of packaging materials can be used which comprise layerswhich are laminated to each other in a manner well known in the priorart. These materials include 1) a polyester layer laminated to a heatactivated sealant layer; 2) a metallized polyester layer laminated to aheat activated sealant layer; 3) a nylon layer laminated to a heatactivated sealant layer; 4) a cellophane layer laminated to a heatactivated sealant layer; 5) a polycarbonate layer laminated to a heatactivated sealant layer; and 6) an acrylic nitrile layer laminated to aheat activated sealant layer.

Though the two groups of materials are to be used to package cheeses,they may also be used to package many foods such as 1) processed cheesewith or without preservatives; 2) cheese blends; 3) pizza toppings; 4)cheese and meat blends; 5) cheese, meat, and condiments blends; 6)mayonnaise; 7) peanut butter; 8) ketchup; 9) bar-b-que sauce; and 10)cheese and eggs. The 10 groups of foods listed above may also bepackaged by a propylene layer coextruded with a polyethylene sealantlayer with an intermediate adhesive layer.

When high density polyethylene is the web material, the sealingtemperature is between 230° F. and 240° F. and the jaws travel with theweb from the first point of engagement to the point of disengagement forapproximately 1/2 to 1 second in a preferred embodiment. In anotherembodiment, the sealing temperature is between 260° and 280° whenpolypropylene is the web material. The pressure exerted between the twoopposing jaws on the sealing section 106 is such that intimate contactbetween the two layers of film is maintained so that substantially allof the cheese is removed from between the two layers of thethermoplastic web material in the cross-sealed areas while. This resultsin a slice of cheese to be defined between adjacent contacting zones ofthe web. Thus, the cheese completely occupies the interior of the volumeof space defined by the hermetically sealed web.

Suitable means are provided for driving the two chain arrangements inthe sealing members 42 and 44. The slices of cheese are defined in thesection between the jaws. Preferably, the sealing section of the jaws 46and 50 are such that the cross seal 102 between adjacent cheese slices100 is approximately 1/4 of an inch. The cleats 46, 50 are spaced intheir respective chains such that the distance from the beginning of oneslice to the beginning of the next slice (including the cross-sealsections 102) is approximately 31/2 inches.

This arrangement allows for high speed production of the individualslices of cheese 100. Since the heating cleats 46 and the mating 50 rideor move along with the cross seal for a fixed period of time, the webmay be continuously moved at a relatively fast pace providing a rapidproduction rate. For example, the web may be moved at approximately 300feet/minute or such that over approximately 1,000 slices are producedper minute.

THE CUTTING AND STACKING ARRANGEMENT

After the cross seals 102 have been formed, the web is then conveyed toa cutting station 62. Loop control means 63 and tensioning means 67 arealso provided. Referring specifically to FIGS. 5 and 7, the cuttingstation includes a pair of spindles 64, 66 with means for severing theweb at the cross seals such that individual slices are defined. Afterthe web has been cut to form the individual slices, the slices of cheese100 are ready to be stacked into individual stacks for packaging. Theslices 100 are discharged from the cutting section 62 and disposed onthe stacker 70. Referring now specifically to FIGS. 6 and 7, a preferredembodiment of the stacker of the present invention is disclosed. Thestacker 70 provides an efficient way for selectively stacking apredetermined number of the cheese slices 100 being produced by thepreviously discussed forming, sealing and cutting arrangement into aplurality of stacks.

The stacking arrangement 70 comprises a porous conveyor belt, which ispreferably in the form of an endless belt 72. Preferably, the endlessbelt 72 includes a plurality of apertures such that the belt 72 isapproximately 25% or more open. A vacuum system 78 is provided on theinside of the endless belt 72 such that the slices of cheese 100 aremaintained on the outside surface of the endless belt 72 by theatmospheric pressure differential pressure created by the vacuum system78. Preferably the endless belt 72 rotates about two rollers or drums 74and 76 which are rotated by means known in the art. The vacuum system 78provides sufficient vacuum such that the slices of cheese 100 adhere tothe surface of the belt 72 as the belt is advanced. That is, the slicesof cheese 100 are maintained on the belt as the belt travels around thedrum 76 and further are maintained even in an upside down position asthe slices 100 travel around and are disposed on the bottom of thestacker 70. Thus, the vacuum of the vacuum system 78 is sufficient toovercome the force of gravity pulling the slice of cheese 100 down whenit is on the bottom of the belt 72.

A plurality of stacking locations 82a-82f are provided to accommodatethe rapid production rate of the wrapping system described above.

An air ejector 80a-80f is provided at the front of each stackinglocation 82a-82f. The air ejector 80a-80f, when actuated, applies airpressure at the leading edge of the cheese slice 100 as it travels onthe belt 72. The ejector 80a-80f provides the positive air pressurethrough the apertures of the belt as the slice passes under it tothereby override the vacuum and "peel off" the cheese slice 100 as it isbeing conveyed past the ejector 80a-80f. In this manner, the force ofgravity releases the slice 100 into the desired stacking location.Preferably, an inclined plate or ramp plate 90 is provided before thefront edge of each stacking location 82a-82f. This ramp plate 90 assuresthat if the cheese slice 100 is released from the conveyor belt 70before it is fully in the stacking location, the cheese slice 100 willslide onto the plate 90 and be conveyed into the stacking location. Aphoto sensor 84 is provided at the beginning of the stacking locationfor programming the number of slices 100 to be dropped at each stackinglocation 82.

In a preferred embodiment, a particularly advantageous stacking systemis configured such that an intermediate slice receiving means is used totemporarily hold the first few slices being dropped into the stackinglocation 82. In one preferred embodiment, the intermediate slicereceiving means comprises a first or upper set of retractable fingerlikemembers 86. Preferably, a lower set of retractable fingerlike members 88are also provided. The upper set of retractable fingers 86 are disposedat an intermediate level between the top of the particular stackinglocation and the bottom of the stacking location. This upper set ofstacking fingers 86 acts as an intermediate landing stop for the cheeseslices 100 as they are peeled off into the particular stacking location.After a predetermined number of slices have fallen on to the upper setof fingers 86, the fingers 86 are retracted such that the slices ofcheese 100 which were stacked in the particular stacking locations fallonto the lower set of fingers 88. The lower set of fingers 88 isparticularly important where the number of slices 100 that is to bestacked in each stacking location is large. For example, some projectsmay require as much as a four inch stack of slices of cheese 100. Theadvantages of the upper set of fingers 86 are best illustrated bydescribing the trajectory of the cheese slices 100 if this upper set ofretractable fingers 86 were not present. As the slice 100 would bepeeled off by the ejector 80, the slice 100 would begin to fall at anangle with the leading edge of the slice 100 having the lowest position.If the slice 100 were to fall a sufficient distance, it would tumblerather than being flatly deposited in an orderly fashion therebydisrupting the stacking process. The upper fingers 86 provide anintermediate stop for the slices 100. The slice 100 only falls a shortdistance to the upper set of finger 86. Thus, the stability of the stackis maintained.

After a number of 100 slices have been disposed on to the upper set offingers 86, the upper retractable fingers 86 are retracted and theentire stack of slices 100 falls onto the lower set of retractablefingers 88. Since a number of slices 100 have already been deposited onthe stack, the slices 100 which are now being peeled off from theconveyor 72 and dropped onto the existing stack of slices 100 will havea shorter distance to fall. That is, the distance that a falling slice100 will have to fall will only be the distance between the conveyorbelt 70 and the top of the stack. After all of the slices 100 that areto be included in a particular stack have been stacked, the lower set ofretractable fingers 88 is retracted and the stack of slices 100 fallsonto the conveyor table 92.

In another preferred embodiment, the intermediate slice receiving meansmay comprise an elevator arrangement which is initially raised to apredetermined intermediate height and is lowered to accommodate the rateat which the slices are being stacked in the stacking locations.Preferably, in this embodiment, the elevator is lowered to deliver thestack to a conveyor table 92 after the last slice 100 has been droppedin the stack.

Preferably means such as a programmable controller or microprocessor areoperatively connected to the respective ejectors 80a-80f at eachstacking location 82a-82f such that the number of slices 100 in thestacks 82a-82f can be selectively adjusted. The controlling means willalso make it possible to only fill certain stacking locations andeliminate other stacking locations. In one particularly advantageousembodiment, the ejectors 80a-80f and the control means are operativelyconfigured such that each stacking location 82a through 82f issuccessively or sequentially filled. In this embodiment, before any ofthe stacking locations 82a-82f have been filled, all of the ejectorsprovide positive pressure at the front edge of each stacking location.As the slice 100 is conveyed past the first ejector 80 (corresponding tothe first stacking location 82a), the first ejector 80 provides positivepressure to peel the slice 100 off the conveyor belt 72 and into thefirst stacking location 82a. After the predetermined number of slices100 have been dropped into the first stacking location 82a, the positivepressure provided by the ejector means 80a at the first stackinglocation is terminated. Thus, the vacuum pressure from the vacuum means78 will continue to hold the next slice 100 on the conveyor belt 72until it reaches the ejector 80a at the second stacking location 82b.The ejector 80b at the second stacking location 82b will continue tooperate until the second stack has been filled with the predeterminednumber of slices. After the second stack has been filled, the ejector80b at the beginning of the second stacking location 82b will be turnedoff and thus the next slice 100 will be conveyed to the third stackinglocation 82c. This process will continue until the predetermined numberof slices for each stacking location is complete. This process isparticularly advantageous since the vacuum system does not have to berepeatedly disengaged. The air ejectors override the vacuum without theneed to discontinue its operations.

Preferably, as illustrated in FIGS. 1 and 5, the stacks from eachindividual location 82a through 82f are disposed onto another conveyor92 which is disposed such that it advances in a direction transverse tothe direction of movement of the endless belt 72 of the stacker 70. Inthis manner, the stacks of the slices 100 are conveyed away from thestacker 72 to a location where they may be further processed eithermanually or automatically.

Therefore, the packaging and stacking system of the present inventionprovide a means for hermetically packaging individual slices of cheeseat an efficient and rapid production rate. The sealing arrangementprovided by the present invention provides a hermetic seal along thelongitudinal edge of the web. After the cheese is inserted in thetubular web, hermetically sealed cross seals are formed. Thisarrangement provides a hermetically sealed package of cheese which willhave a substantially longer shelf life than the presently availablesliced cheese products. Additionally, the longitudinal seal and thecross seals are provided in a manner which permits continuous movementof the web without the intermittent action of some presently availablesealing systems. The slice which is produced and packaged according tothe present invention provides a preferred final packaged product. Theseal is formed between the two inner layers of the low thermal meltmaterial such that the seal is broken when the packaging materials arepulled apart to open the individual slice. Unlike presently availablepackages, Wherein the sealing layer is delaminated from the top layer ofthe packaging material and when the package is opened a rough tear ismade which leads to "stringing". With the package of the presentinvention, the bond is broken between the two sealing layers ofpolyethylene and a nice clean opening is provided which eliminates thestringing problem.

Additionally, since the polyethylene may be used as the sealing layer,the packaging material is easily released from the processed cheese.This obviates the need for items such as a shear pump to process thecheese so as to have a less cohesive texture and provide a betterrelease. The process and apparatus of the present invention also permitthe top layer of the packaging material to be made of a high densitypolyethylene material. This is particularly advantageous since highdensity polyethylene is less expensive than presently used materialssuch as MYLAR.

The present invention also provides an efficient stacker which takesslices produced by a relatively rapid production machine and stacks theslices in a plurality of stacks. The number of slices may be selectivelyvaried in the stacking locations allowing for greater control in theproduction process.

The foregoing description of the preferred embodiments of the presentinvention has been presented for purposes of illustration anddescription. The described embodiments are not intended to be exhaustiveor to limit the invention to the precise form disclosed. Obviously manymodifications and variations are possible in light of the aboveteachings. The embodiments which were described were chosen in order tobest explain the principles of the invention and its practicalapplications. It is intended that the scope of the invention be definedby the following claims, including all equivalents.

We claim:
 1. A process for automatically and continuously packaging afood item into hermetically sealed individual slices, comprising thesteps of:providing a continuous web of heat-sealable plastic materialextending lengthwise, the web having front and rear sheets, a web widthdefined by the distance the web extends transverse to the web length,and two edges extending along the web length that can be sealedtogether; folding the web about the web length; moving the web in aforward direction; sealing the edges of the web to form a longitudinalhermetic seal, thereby defining a continuous tubular web; inserting thefood item into the tubular web; flattening the web after the food itemis inserted to form a continuous slice of the flattened food itemdisposed between the front and rear sheets of the web; urging the frontand rear sheets of the web together at predetermined intervals along theflattened web to define a plurality of cross-sealing zones, and applyingsufficient pressure at the cross-sealing zones to remove substantiallyall of the food item from between the front and rear sheets; forming aplurality of hermetically sealed cross-seals at the cross-sealing zonesby heating the web at the cross-sealing zones for a period of time andat a temperature sufficient to hermetically seal the front and rearsheets of the web together at the cross-sealing zones, the cross-sealseach extending continuously along the web width to form, together withthe longitudinal hermetic seals, hermetically sealed packages entirelyenclosing the individual slices of the food item; and cooling the webafter the web is flattened and before the cross-seals are formed.
 2. Theprocess of claim 1, wherein the web is continually moved in a forwarddirection during the sealing of the web edges and during the formationof the cross-seals.
 3. An apparatus for packaging a food item intoindividual slices, comprising:means for folding a continuous web ofthermoplastic material extending lengthwise, the web having front andrear sheets, a web width defined by the distance the web extendstransverse to the web length, and two edges extending along the weblength that can be sealed together; a longitudinal sealing station thatcontinuously forms a hermetic longitudinal seal that joins the two edgesof the web, thereby defining a continuous tubular web; means forinserting the food item into the continuous tubular web of plasticmaterial; a device for continuously flattening the web with the insertedfood item inside the web to form a continuous slice of the flattenedfood item disposed between the front and rear sheets of the web; across-sealing station disposed downstream of the longitudinal sealingstation for urging the front and rear sheets of the web together atpredetermined intervals along the flattened web to define a plurality ofcross-sealing zones, and for applying sufficient pressure at thecross-sealing zones to remove substantially all of the food item fromthe cross-sealing zones, the cross-sealing station forming a pluralityof hermetically sealed cross-seals at the cross-sealing zones by heatingthe web at the cross-sealing zones for a period of time and at atemperature sufficient to hermetically seal the front and rear sheets ofthe web together at the cross-sealing zones, the cross-seals separatingadjacent food item slices and each extending continuously along the webwidth to form, together with the longitudinal hermetic seals,hermetically sealed packages entirely enclosing the individual slices ofthe food item; means for continuously conveying the web from thelongitudinal sealing station to the cross-sealing station; and means forcooling the web after the web is flattened and before the cross-sealsare formed.
 4. The apparatus of claim 3, wherein the food item ischeese.
 5. The apparatus of claim 3, wherein the plastic materialincludes polypropylene.
 6. The apparatus of claim 3, wherein the plasticmaterial is a thermoplastic that includes a high density polyethylenelayer coextruded with a polyethylene sealant layer having anintermediate adhesive layer.
 7. The apparatus of claim 6, wherein thetemperature used to hermetically the cross-seals is between about 230°F. and 240° F.
 8. The apparatus of claim 3, wherein the length of eachcross-seal between adjacent cheese slices is approximately one-quarterinch.
 9. The apparatus of claim 3, wherein the means for cooling the webincludes a tank containing water at a temperature of approximatelybetween 32° F. and 50° F.
 10. The apparatus of claim 3, wherein thecross-sealing station includes first and second sealing members, with atleast one of the sealing members being capable of being heated, and oneof the sealing members being made of a softer material than the othersealing member.
 11. A process for automatically and continuouslypackaging a food item into hermetically sealed individual slices,comprising the steps of:providing a continuous web of heat-sealableplastic material extending lengthwise, the web having front and rearsheets, a web width defined by the distance the web extends transverseto the web length, and two edges extending along the web length that canbe sealed together; folding the web about the web length; continuouslymoving the web in a forward direction; sealing the edges of the web asthe web is continuously moved forward to form a longitudinal hermeticseal, thereby defining a continuous tubular web; inserting the food iteminto the tubular web; flattening the web after the food item is insertedto form a continuous slice of the flattened food item disposed betweenthe front and rear sheets of the web; cooling the web; urging the frontand rear sheets of the web together at predetermined intervals along theflattened web to define a plurality of cross-sealing zones, and applyingsufficient pressure at the cross-sealing zones to remove substantiallyall of the food item from between the front and rear sheets, as the webis continuously moved forward; and forming a plurality of hermeticallysealed cross-seals at the cross-sealing zones by heating the web at thecross-sealing zones for a period of time and at a temperature sufficientto hermetically seal the front and rear sheets of the web together atthe cross-sealing zones as the web is continuously moved forward, thecross-seals each extending continuously along the web width to form,together with the longitudinal hermetic seals, hermetically sealedpackages entirely enclosing the individual slices of the food item. 12.The process of claim 11, further comprising a series of heat-sealingelements associated and moving with the cross-seals as the webcontinuously moves forward, wherein the heat-sealing elements areadjacent or adjoining the associated cross-seals for a predeterminedtime.
 13. The process of claim 11, wherein the web is cooled to atemperature of between approximately 40° F. and 50° F.
 14. A process forautomatically and continuously packaging a cheese formulation intohermetically sealed individual slices, comprising the steps of:providinga continuous web of heat-sealable plastic material extending lengthwisewith opposing edge portions; folding the web longitudinally; sealing theedge portions of the web to form a longitudinal hermetic seal, therebydefining a continuous tube; introducing the cheese along the web;flattening the tube after the cheese is inserted to form a continuousflat ribbon of the cheese disposed within the flattened tube; urgingportions of the flattened tube together at predetermined intervals todefine a plurality of cross-sealing zones, and applying sufficientpressure at the cross-sealing zones to eliminate substantially all ofthe cheese from the cross-sealing zones; and heating the cross-sealingzones for a period of time and at a temperature sufficient tohermetically seal the cross-sealing zones to form, with the longitudinalhermetic seal, hermetically sealed individual packages entirelyenclosing individual slices of the cheese; wherein the web iscontinuously moved in the forward direction during the steps of folding,sealing the edge portions, flattening the tube and sealing thecross-sealing zones.
 15. The process of claim 14, wherein the web iscontinually moved in a forward direction during the sealing of the edgeportions of the web and during the formation of the cross-seals, at arate sufficient to produce in excess of 700 hermetically sealedinndividual cheese packages per minute.
 16. The process of claim 14,wherein the web is continually moved in a forward direction during thesealing of the edge portions of the web and during the formation of thecross-seals, at a rate sufficient to produce in excess of approximately1000 hermetically sealed individual cheese packages per minute.
 17. Theprocess of claim 14, further comprising the step of cooling the webafter the web is flattened and before the cross-seals are formed.
 18. Anapparatus for packaging a cheese formulation into individual slices,comprising:a device for folding a web of thermoplastic materialextending lengthwise with opposing edge portions, the web having a widthdefined by the distance the web extends transverse to its length; alongitudinal sealing station that continuously seals the edge portionsof the web to form a longitudinal hermetic seal, thereby defining acontinuous tube; means for inserting the cheese into the tube; a devicefor flattening the tube after the cheese is inserted to form acontinuous flat ribbon of the cheese disposed within the flattened tube;a cross-sealing station disposed downstream of the longitudinal sealingstation for urging portions of the flattened tube together atpredetermined intervals to define a plurality of cross-sealing zonesextending across the entire web width and separating adjacent cheeseslices, for applying sufficient pressure at the cross-sealing zones toeliminate substantially all of the cheese from the cross-sealing zones,and for heating the cross-sealing zones for a period of time and at atemperature sufficient to hermetically seal the cross-sealing zones toform, with the longitudinal hermetic seal, hermetically sealedindividual packages entirely enclosing individual slices of the cheese;and means for continuously conveying the web in a forward direction fromthe longitudinal sealing station to the cross-sealing station.
 19. Theapparatus of claim 18, further comprising means for cooling the webafter the web is flattened and before the cross-seals are formed. 20.The apparatus of claim 19, wherein the means for cooling the webincludes a tank containing water at a temperature of approximatelybetween 32° F. and 50° F.
 21. The apparatus of claim 18, wherein thethermoplastic material includes polypropylene.
 22. The apparatus ofclaim 18, wherein the temperature used to hermetically seal thecross-seals is between about 230° F. and 240° F.
 23. The apparatus ofclaim 18, wherein the length of each cross-seal between adjacent cheeseslices is approximately one-quarter inch.
 24. The apparatus of claim 18,wherein the cross-sealing station includes a first and a second seriesof sealing members, with at least some of the first series sealingmembers being heated, and the second series of sealing memberscomprising a resilient material.
 25. The apparatus of claim 18, whereinthe apparatus is capable of producing in excess of 700 hermeticallysealed individual cheese packages per minute.
 26. The apparatus of claim18, wherein the apparatus is capable of producing in excess ofapproximately 1000 hermetically sealed individual cheese packages perminute.